1. Field of the Invention
The present invention relates generally to improvements in breast pumps, and more particularly pertains to new and improved electric breast pumps wherein the breast pump both expresses and collects breast milk.
2. Description of Related Art
In the field of breast pumps for expressing breast milk it has been the practice to employ hard breast cups and maximum suction to the human teat to express the breast milk. Such devices have not been entirely satisfactory in that if the suction generated by the breast pump is too high, bruising will be caused to the areola and nipple. In addition, the amount of milk volume obtained in response to a constant average suction is quite low compared to that obtained by a suckling infant. A breast feeding infant, in addition to applying suction, compresses the teat against his hard palate and uses the peristaltic action of the tongue. A research study entitled Comparing Breastfeeding and Breast Pumps Using a Computer Model, published in the Journal of Human Lactation, 1997, Vol. 13, pp. 195 to 202, by Christopher Xoppou, Ph.D., et al., concluded that a large increase in milk flow can be obtained when both cyclic suction and peristaltic force is used on the human teat. The present invention simulates an infant suckling by utilizing both peristaltic forces and cyclic suction.
The objects of the present invention are achieved by use of soft breast cups made of durable, yet flexible, plastic material that collapse around the human teat during a portion of each suction cycle. Suction is created by an electric motor driving a piston vacuum pump that draws a continuous suction airflow. The suction cycle is caused by a magnetic valve controlled by a vacuum sensor that causes the valve to open the vacuum line to atmosphere when a pre-set maximum pressure is reached and closes again when pressure is released. Motor speed and maximum pressure is selectable by the user. The suction may be adjusted between 150 mm Hg to 250 mm Hg. The motor speed is adjustable between these different speeds to vary the suction frequency from about 20 to 44 cycles per minute. The suction and cycle adjustment, along with the flexible, collapsing cups, provides for greater comfort and optimized milk flow. Besides collection bottles, one for each of the two breast cups, the system uses a catch bottle in the suction tube, before it is connected to the vacuum pump, to catch any breast milk that happens to accidentally flow past a collection bottle. The catch bottle prevents the breast milk from entering the vacuum pump. Milk flow into the catch bottle will trigger a light sensor that causes the motor to stop.